1. Field of the Invention
This invention relates to an improvement of a fuel injector wherein the shape of a component part is simplified so that the part can be readily produced and assembled with high accuracy in a simple operation.
2. Description of the Prior Art
A conventional fuel injector is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2-66380. This fuel injector will be described with reference to FIGS. 5 and 6 showing a vertical-sectional view thereof and a cross-sectional view taken along the line VI--VI of FIG. 5, respectively.
As shown in FIG. 5, a solenoid coil 103 is disposed on the lower periphery of a ferromagnetic metal tubular core 101. A ferromagnetic metal tubular connector 139 is connected via a ferromagnetic metal medium 106 to the lower end of the core 101. A tubular armature 112 is slidably disposed within the connector 139. The armature 112 is connected via a connecting tube 136 to a spherical valve 114. The connector 139 holds a valve seat 108 having an injection hole 117. The armature 112, the connecting tube 136 and the spherical valve 114 are attracted upward together by the solenoid coil 103 to thereby open the injection hole 117. The spherical valve 114 is biased in a closing direction by a return spring 118.
Outer peripheries of a part of the core 101 and the solenoid coil 103 are surrounded together by a plastic jacket 124. A pair of outside magnetic path forming members 128 made of ferromagnetic metal material are embedded in the jacket 124 while confronting each other as shown in FIG. 6.
As shown in FIG. 5, the outside magnetic path forming members 128 surround the solenoid coil 103, the core 101 and the connector 139 together. Each member 128 has such a complex shape as surrounding the solenoid coil 103, and has an axially extending end portion 132 in its upper part. The upper end portion 132 of the outside magnetic path forming member 128 is in contact with the core 101, while a lower end portion 132a thereof is in contact with the connector 139.
According to the conventional fuel injector, each of the paired outside magnetic path forming members 128 is fabricated by a band plate whose both ends are substantially bent into Z-shape. This construction makes the shape of the member 128 rather complicated, thus making it difficult to produce the members 128. Further, there is another problem in that the outside magnetic path forming members 128 should be fixed to the core 101 by welding or like operations after they are axially and circumferentially positioned in advance, thus making it complicated to assemble them.